1. Field of the Invention
The present invention relates generally to medical devices and methods for their fabrication. In particular, the invention relates to a tool for loading a small diameter flexible imaging core into a catheter body.
2. Description of the Relevant Art
Intravascular imaging of blood vessel lesions prior to percutaneous transluminal angioplasty, arthrectomy, and other interventional procedures, is of great benefit. A particularly successful design for an intravascular imaging apparatus employs a rotatable ultrasonic transducer, where the transducer is attached to the distal end of a flexible drive cable or imaging core. The transducer may be disposed within a catheter body or sheath and rotated in order to transmit an ultrasonic signal and produce a video image by well-known techniques.
To be compatible with introduction of the catheter into very small coronary arteries, the imaging core is reduced to correspondingly small diameters. In addition to the small diameter, the drive cable is made highly flexible so that it can pass through tortuous regions of the vasculature, particularly the coronary arteries.
However, as the diameter of the imaging core is reduced, the imaging core tends to lose column strength. Unfortunately, an imaging core with decreased column strength is inclined to collapse or buckle as the imaging core is advanced into the catheter lumen and encounters any type of increased friction due to sharp bends or constrictions, causing the axial load to reach its critical value. This occurrence is problematic since imaging cores are typically loaded into catheters by hand, which means that practitioners must be very precise in order to properly load the imaging core without damaging the imaging core. The problem of loading and advancing the imaging core can be compounded when the imaging core is loaded during clinical use, when the inner lumen of the catheter is typically wet. The surface tension forces present in any fluid on the inner lumenal wall will increase friction, which prevents easy insertion of the imaging core.
For these reasons, it would be desirable to provide a tool for loading a small diameter flexible imaging core having reduced pushability into a catheter body, where use of the tool can reduce bending, kinking, or buckling of the flexible imaging core as the core is advanced into an inner lumen of a catheter body.